Directional drilling is a well established art in the well drilling industry. Various elements are available for inclusion in the drill string to influence the course of the well bore as drilling progresses. Apparatus for use downhole to indicate at the surface various parameters measured downhole are now in common use and generally known as Measurement While Drilling or MWD arrangements. At the present time the drill string often has to be oriented rotationally relative to earth to measure and influence the course of the well bore as it is further drilled.
Frequent measurements and corrections now practical demand only small amounts of bend in drill strings to deflect the drill string centerline to make well bore corrections. It is practical to rotate the drill string with such slight bends to drill ahead along the existing centerline. There are two salient problems in making up the downhole assembly to drill with bent elements, commonly known as bent subs, whatever their length. The first problem pertains to rotational alignment of drill string components separated by threaded connections. The second problem pertains to adjustably bending the bent sub to deflect the centerline of the lower portion of the string relative to the upper portion. Apparatus of this invention addresses those two problems.
It is therefore an object of this invention to provide an adjustable sub to change the rotational orientation of axially spaced portions of a drill string.
It is another object of this invention to provide an adjustable sub to deflect the centerline of a drill string.
It is yet another object of this invention to provide adjustable subs that require no shims and may complete the adjustment by the application of torque in the manner used on tool joints, with the same tongs.
It is still a further object of this invention to provide adjustable subs for use in drilling motor housings to change the orientation of the lower end relative to the upper end of the bodies.
These and other features and advantages will be apparent to those skilled in the art from consideration of the included claims and appended drawings.